Livery Details
The prototype/testbed livery applied to the first 737-100, and the first aircraft of the 737 family as a whole.
(N73700 pictured.)
Optional: Image or Link to Reference
Here’s a closer view of the nose markings, displaying what I assume to be the airlines in support of the aircraft/family:
Why should this livery be added?
I’d say this livery should be added because of its historical value and significance in aviation history, serving as the identity of the first aircraft of the 737 family - which in itself had a really unique role to go with it, being used for testing and qualifying the aircraft’s design, before later being transferred to NASA for use as a flying laboratory, and is even preserved to this day.
Additionally, being a rare aircraft type already, this would be awesome to see with the B731 whenever it’s implemented, making for great special arrival/event material.